Systems and methods for creating and displaying a user interface for displaying hierarchical data

ABSTRACT

A graphical user interface for displaying hierarchical data, such as extensible markup language (XML) data, in hypertext markup language (HTML) format in a convenient and efficient manner. For data having subordinate data, an actuatable subordinate data indicator is displayed on the user interface. When actuated, the subordinate data is displayed in a similar format as the parent data. Two methods are described for building the tables. A first method initially parses all the data and builds the necessary tables for display. A second method initially parses only the top level of data and then builds subordinate tables as they are requested by a user.

RELATED APPLICATIONS

This application is a Continuation of prior application Ser. No.09/883,125, filed Jun. 15, 2001.

TECHNICAL FIELD

The systems and methods described herein relate generally to graphicaluser interfaces for computing systems and, more particularly, userinterfaces for displaying hierarchical data (such as extensible markuplanguage (XML) data) in hypertext markup language (HTML).

BACKGROUND

Extensible markup language (XML) is a more recent of a line of severalevolutions of a general markup language that was invented years ago as acommon style sheet for technical reports. From this general markuplanguage evolved hypertext markup language (HTML) that made possible theWorld Wide Web.

Before XML, markup languages focused on describing the layout for apage, typically on computer screens. The layout defined such things astext fonts, text location, image location, background color, etc. Webpages written in HTML can be rendered by any web browser applicationrunning on almost any kind of computer. The web page will look andfunction virtually identically without regard for the computingenvironment.

However, HTML has no way of “knowing” the meaning of the data that itdisplays. It is only capable of describing how the Web page will lookand function and what text it will contain. While HTML knows a greatdeal about words, it knows nothing at all about information.

On the other hand, XML differs from those markup languages in that XMLfocuses on describing data, not pages. Hence, XML makes applicationsaware of what the application are about. XML makes Web pagesintelligent. For example, a spreadsheet application written with XML canlink across the Internet into other spreadsheets and into server-basedapplications that offer even greater power.

XML introduced the concept of metadata, i.e., data about data. In XML,each piece of data not only includes the data itself but also adescription of the data, what it means. An XML database can have a listof names (data) and a tag on the data saying that the names are customernames (metadata). An XML search engine does not have to pull in all thedata and analyze the data to find a list of customer names, it simplyqueries the metadata to find tags indicating that the names are customernames and only that data has to be retrieved.

XML data is hierarchical. In other words, there are different levels ofdata, some levels subordinate to others. For example, an XML documentmay contain a first level of data items wherein each data item is acustomer name. Each first-level data item (customer name) may haveseveral attributes (contained in fields) and/or one or moresecond-level, or subordinate, data items. In the example where thefirst-level data items are customer names, each customer name may havesecond-level data items that comprise customer orders. The second-leveldata items may, in turn, have subordinate data levels (third-level dataitems). In the example described, the second-level data items (customerorders) may have subordinate data items, e.g., order details, and so on.

Despite all the advantages that accompany XML, XML cannot format data.Therefore, a formatting language must still be utilized to display XMLdata. Providing an efficient way to display XML—or, in fact, anyhierarchical data—using HTML is an important goal to assist applicationdevelopers and users of XML-based applications.

SUMMARY

A graphical user interface for displaying hierarchical data—such asextensible markup language (XML) data—in hypertext markup language(HTML) is described that includes an actuatable subordinate dataindicator that, when actuated, causes data that is subordinate to thedisplayed data to be displayed.

Methods are described for parsing the hierarchical data to build thedisplay. One method requires that the complete data be initially parsedto build hierarchical tables that may be displayed on command. Anothermethod describes building the tables on demand, so that only the datathat is requested to be viewed must have a table built to display therequested data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary computer system on which thedescribed invention may be implemented.

FIG. 2 is an illustration of an example display showing first-level dataitems.

FIG. 3 is an illustration of an example display showing second-leveldata items.

FIG. 4 is an illustration of an example display showing third-level dataitems.

FIG. 5 is a flow diagram depicting a recursive method for building adisplay from hierarchical data.

FIG. 6 is a flow diagram depicting a dynamic nested table creationmethod for building a display from hierarchical data.

DETAILED DESCRIPTION

FIG. 1 illustrates an example of a suitable computing environment 100within which a centralized alert delivery system as described herein,may be implemented (either fully or partially). The computingenvironment 100 may be utilized in the computer and networkarchitectures described herein.

The exemplary computing environment 100 is only one example of acomputing environment and is not intended to suggest any limitation asto the scope of use or functionality of the computer and networkarchitectures. Neither should the computing environment 100 beinterpreted as having any dependency or requirement relating to any oneor combination of components illustrated in the exemplary computingenvironment 100.

The centralized alert delivery system may be implemented with numerousother general purpose or special purpose computing system environmentsor configurations. Examples of well known computing systems,environments, and/or configurations that may be suitable for useinclude, but are not limited to, personal computers, server computers,thin clients, thick clients, hand-held or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputers, mainframe computers,distributed computing environments that include any of the above systemsor devices, and the like.

The centralized alert delivery system may be described in the generalcontext of computer-executable instructions, such as program modules,being executed by a computer. Generally, program modules includeroutines, programs, objects, components, data structures, etc. thatperform particular tasks or implement particular abstract data types.The centralized alert delivery system may also be practiced indistributed computing environments where tasks are performed by remoteprocessing devices that are linked through a communications network. Ina distributed computing environment, program modules may be located inboth local and remote computer storage media including memory storagedevices.

The computing environment 100 includes a general-purpose computingdevice in the form of a computer 102. The components of computer 102 caninclude, by are not limited to, one or more processors or processingunits 104, a system memory 106, and a system bus 108 that couplesvarious system components including the processor 104 to the systemmemory 106.

The system bus 108 represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, sucharchitectures can include an Industry Standard Architecture (ISA) bus, aMicro Channel Architecture (MCA) bus, an Enhanced ISA (EISA) bus, aVideo Electronics Standards Association (VESA) local bus, and aPeripheral Component Interconnects (PCI) bus also known as a Mezzaninebus.

Computer 102 typically includes a variety of computer readable media.Such media can be any available media that is accessible by computer 102and includes both volatile and non-volatile media, removable andnon-removable media.

The system memory 106 includes computer readable media in the form ofvolatile memory, such as random access memory (RAM) 110, and/ornon-volatile memory, such as read only memory (ROM) 112. A basicinput/output system (BIOS) 114, containing the basic routines that helpto transfer information between elements within computer 102, such asduring start-up, is stored in ROM 112. RAM 110 typically contains dataand/or program modules that are immediately accessible to and/orpresently operated on by the processing unit 104.

Computer 102 may also include other removable/non-removable,volatile/non-volatile computer storage media. By way of example, FIG. 1illustrates a hard disk drive 116 for reading from and writing to anon-removable, non-volatile magnetic media (not shown), a magnetic diskdrive 118 for reading from and writing to a removable, non-volatilemagnetic disk 120 (e.g., a “floppy disk”), and an optical disk drive 122for reading from and/or writing to a removable, non-volatile opticaldisk 124 such as a CD-ROM, DVD-ROM, or other optical media. The harddisk drive 116, magnetic disk drive 118, and optical disk drive 122 areeach connected to the system bus 108 by one or more data mediainterfaces 126. Alternatively, the hard disk drive 116, magnetic diskdrive 118, and optical disk drive 122 can be connected to the system bus108 by one or more interfaces (not shown).

The disk drives and their associated computer-readable media providenon-volatile storage of computer readable instructions, data structures,program modules, and other data for computer 102. Although the exampleillustrates a hard disk 116, a removable magnetic disk 120, and aremovable optical disk 124, it is to be appreciated that other types ofcomputer readable media which can store data that is accessible by acomputer, such as magnetic cassettes or other magnetic storage devices,flash memory cards, CD-ROM, digital versatile disks (DVD) or otheroptical storage, random access memories (RAM), read only memories (ROM),electrically erasable programmable read-only memory (EEPROM), and thelike, can also be utilized to implement the exemplary computing systemand environment.

Any number of program modules can be stored on the hard disk 116,magnetic disk 120, optical disk 124, ROM 112, and/or RAM 110, includingby way of example, an operating system 126, one or more applicationprograms 128, other program modules 110, and program data 132. Each ofsuch operating system 126, one or more application programs 128, otherprogram modules 130, and program data 132 (or some combination thereof)may include an embodiment of a communications layer and a subscriptionlayer of the centralized alert delivery system.

A user can enter commands and information into computer 102 via inputdevices such as a keyboard 134 and a pointing device 136 (e.g., a“mouse”). Other input devices 138 (not shown specifically) may include amicrophone, joystick, game pad, satellite dish, serial port, scanner,and/or the like. These and other input devices are connected to theprocessing unit 104 via input/output interfaces 140 that are coupled tothe system bus 108, but may be connected by other interface and busstructures, such as a parallel port, game port, or a universal serialbus (USB).

A monitor 142 or other type of display device can also be connected tothe system bus 108 via an interface, such as a video adapter 144. Inaddition to the monitor 142, other output peripheral devices can includecomponents such as speakers (not shown) and a printer 146 which can beconnected to computer 102 via the input/output interfaces 140.

Computer 102 can operate in a networked environment using logicalconnections to one or more remote computers, such as a remote computingdevice 148. By way of example, the remote computing device 148 can be apersonal computer, portable computer, a server, a router, a networkcomputer, a peer device or other common network node, and the like. Theremote computing device 148 is illustrated as a portable computer thatcan include many or all of the elements and features described hereinrelative to computer 102.

Logical connections between computer 102 and the remote computer 148 aredepicted as a local area network (LAN) 150 and a general wide areanetwork (WAN) 152. Such networking environments are commonplace inoffices, enterprise-wide computer networks, intranets, and the Internet.

When implemented in a LAN networking environment, the computer 102 isconnected to a local network 150 via a network interface or adapter 154.When implemented in a WAN networking environment, the computer 102typically includes a modem 156 or other means for establishingcommunications over the wide network 152. The modem 156, which can beinternal or external to computer 102, can be connected to the system bus108 via the input/output interfaces 140 or other appropriate mechanisms.It is to be appreciated that the illustrated network connections areexemplary and that other means of establishing communication link(s)between the computers 102 and 148 can be employed.

In a networked environment, such as that illustrated with computingenvironment 100, program modules depicted relative to the computer 102,or options thereof, may be stored in a remote memory storage device. Byway of example, remote application programs 158 reside on a memorydevice of remote computer 148. For purposes of illustration, applicationprograms and other executable program components such as the operatingsystem are illustrated herein as discrete blocks, although it isrecognized that such programs and components reside at various times indifferent storage components of the computing device 102, and areexecuted by the data processor(s) of the computer.

Computer-Executable Instructions

An implementation of a user interface for displaying hierarchical datamay be described in the general context of computer-executableinstructions, such as program modules, executed by one or more computersor other devices. Generally, program modules include routines, programs,objects, components, data structures, etc. that perform particular tasksor implement particular abstract data types. Typically, thefunctionality of the program modules may be combined or distributed asdesired in various embodiments.

Exemplary Operating Environment

FIG. 1 illustrates an example of a suitable operating environment 100 inwhich a user interface for displaying hierarchical data may beimplemented. Specifically, the centralized alert delivery system(s)described herein may be implemented wholly or in part by any programmodules 128-130 and/or operating system 128 in FIG. 1 or a portionthereof.

The operating environment is only an example of a suitable operatingenvironment and is not intended to suggest any limitation as to thescope or use of functionality of the centralized alert deliverysystem(s) described herein. Other well known computing systems,environments, and/or configurations that are suitable for use include,but are not limited to, personal computers (PCs), server computers,hand-held or laptop devices, multiprocessor systems,microprocessor-based systems, programmable consumer electronics,wireless phones and equipments, general- and special-purpose appliances,application-specific integrated circuits (ASICs), network PCs,minicomputers, mainframe computers, distributed computing environmentsthat include any of the above systems or devices, and the like.

Computer Readable Media

An implementation of a user interface for displaying hierarchical datamay be stored on or transmitted across some form of computer readablemedia. Computer readable media can be any available media that can beaccessed by a computer. By way of example, and not limitation, computerreadable media may comprise “computer storage media” and “communicationsmedia.”

“Computer storage media” include volatile and non-volatile, removableand non-removable media implemented in any method or technology forstorage of information such as computer readable instructions, datastructures, program modules, or other data. Computer storage mediaincludes, but is not limited to, RAM, ROM, EEPROM, flash memory or othermemory technology, CD-ROM, digital versatile disks (DVD) or otheroptical storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other medium which canbe used to store the desired information and which can be accessed by acomputer.

“Communication media” typically embodies computer readable instructions,data structures, program modules, or other data in a modulated datasignal, such as carrier wave or other transport mechanism. Communicationmedia also includes any information delivery media.

The term “modulated data signal” means a signal that has one or more ofits characteristics set or changed in such a manner as to encodeinformation in the signal. By way of example, and not limitation,communication media includes wired media such as a wired network ordirect-wired connection, and wireless media such as acoustic, RF,infrared, and other wireless media. Combinations of any of the above arealso included within the scope of computer readable media.

Graphical User Interface: First-Level Data Items

FIG. 2 is an illustration of an exemplary graphical user interface 200for displaying first-level data items in a hierarchical data set. Theuser interface 200 is displayed on a computer monitor screen 202. Alsoshown on the screen 202 are a first toolbar 204 a and a second toolbar204 b similar to those typically displayed by a Web browser.

The graphical user interface 200 includes several rows 206 a-206 j andcolumns 208 a-208 h. Each of the rows 206 a-206 j represents a firstlevel of data items in a hierarchical data set, such as an XML document.Each column 208 a-208 h includes a heading in a heading row 210. Theheadings row 210 includes the heading, respectively, of customer ID(column 208 a), company name (column 208 b), contact (208 c), address(208 d), phone (208 e), orders (208 f), order details (208 g) andcustomer details (208 h). For the present example, most of the contentsof the data items are irrelevant. However, for purposes of the followingdiscussion, the customer id of a customer identified in row 206 a,column 208 a is 3C146HD and the customer id of a customer identified inrow 206 b, column 208 a is 7A654LD.

Columns 208 f (orders), 208 g (order details) and 208 h (customerdetails) include—in some rows—a subordinate data indicator 212. Thesubordinate data indicator 212 is an actuatable icon that, whenactuated, displays a subordinate level of data in the hierarchical dataset. In the present example, a subordinate data indicator 212 isdisplayed in each row 206 a-206 j of column 208 f (orders). Thisindicates that there is data regarding orders for each of the customersindicated in column 208 a-208 h. As will be discussed in greater detail,below, if any of the subordinate data indicators in column 208 f isactuated, then a second level of data will be displayed for the ordersassociated with the customer identified in the row 206 a-206 j in whichthe subordinate data indicator 212 that was actuated is located.

If there is no subordinate data associated with a first-level data item,then no subordinate data indicator corresponding to the first-level dataitem is shown. For example, for customer 3C146HD, there are no orderdetails because no subordinate data indicator 212 is shown in column 208g (order details). However, there are customer details associated withcustomer 3C146HD because a subordinate data indicator 212 is shown incolumn 208 h (customer details) associated with that customer.

Similarly, for customer 7A654LD, there is subordinate data for orders(column 208 f) and order details (column 208 g), but there is nosubordinate data for customer details (208 h). This can be seen by thepresence or absence of a subordinate data indicator 212 in theaforementioned columns.

Graphical User Interface: Second-Level Data Items

FIG. 3 is an illustration of the graphical user interface 200 shown inFIG. 2 after a subordinate data indicator 212 has been actuated in theorders column (208 f) for the customer identified in row 206 a (customerid 3C146HD). The second-level data is displayed in a table 300 similarto the first-level data, although it should be noted that subordinatelevel data items may be displayed in a different format that the formatin which the first-level data items are displayed.

The table 300 includes several rows (302) and columns (304), theintersection of which forms fields. A field may contain a subordinatedata indicator 212 similar to the subordinate data indicators 212 shownin FIG. 2. In this example, the only column 304 that may include asubordinate data indicator 212 is entitled “Details” (column 306). Aspreviously discussed, if the subordinate data indicator 212 is shown ina row in column 306, then the second-level data item in the rowassociated with the column in which the subordinate data indicator 212appears has subordinate—or, third-level—data items.

Graphical User Interface: Third-Level Data Items

FIG. 4 is an illustration of the graphical user interface 200 shown inFIGS. 2 and 3 after a subordinate data indicator 212 has been actuatedin the “details” column (306) of table 300. Third-level data items aredisplayed in a table 400 that is similar to the table 300 shown in FIG.3. Again, the table 400 includes at least one column 402 that mayinclude a subordinate data indicator 212 The subordinate data indicator212 may be actuated to display subordinate (fourth-level) data items.

It is noted that table 300 in FIG. 3 and table 400 in FIG. 4 aredisplayed in a position so that the actuated subordinate data indicator212 that was actuated to display the table 300, 400 and the rowassociated with the actuated subordinate data indicator 212 remainsvisible. This is not required to implement the described user interface,but it can be a convenience for a user.

Recursive Method For Building Display Tables

To build HTML pages from XML data, an extensible style language (XSL) orextensible style (or stylesheet) language transformation (XSLT) scriptmust be created. FIG. 5 is a flow diagram of a method that may be usedto create the user interface described herein for display. Those skilledin the art will recognize that the steps described in FIG. 5 can beaccomplished via an XSL or XSLT script, although the details of such ascript will not be discussed herein.

The method outlined in FIG. 5 is a recursive method that is used toparse the entire hierarchical data set and build tables (or some otherdata structure) for displaying the data in the data set. At block 500, acurrent level of data is identified and initially set to 1 (indicating afirst level of data in the hierarchical data set). A table representingthe first level of data is created and stored at block 502.

At block 504, a current node (or data item) in the current level isidentified. A row is created in the table representing the first levelof data for the current node (block 506). At block 508, it is determinedwhether the current node has subordinate (child) data associated withit. If there is no subordinate data (“No” branch, block 508), then it isdetermined if there is more data to be parsed (block 520). If there ismore data (“Yes” branch, block 520), then a new, or next, node (dataitem) in the current level is identified. Again at block 506, a row iscreated in the table representing the first level of data for the newcurrent node.

If the new current node has subordinate data associated with it (“Yes”branch, block 508), then the current level is set to the current levelplus one (block 510), i.e., the second level of data in the hierarchicaldata. A current node for the new current level is identified at block512 and the process then reverts to block 508 to determine if thecurrent node has subordinate data associated with it. This processcontinues recursively until the bottom level of data is reached. Afterall the data items have been parsed and there is no more data (“No”branch, block 520), then the process terminates and a completerepresentation of the hierarchical data is now stored in memory.

It is noted that this recursive method works well for “flat” data thatdoes not have a large number of levels in it, or for data that hasrelatively few data items, e.g., less than one thousand data items. Fordeep or more extensive data, a “build on demand” method may be moreappropriate for the situation. Such a method is described below withreference to FIG. 6.

Dynamic Nested Table Creation Method For Building Display Tables

FIG. 6 is a flow diagram depicting a method for building the graphicaluser interface depicted in FIGS. 2-4. The described method does notinitially parse all of the data in the hierarchical (XML) data set. Inthe method described in FIG. 6, the subordinate data displays arecreated only upon demand by a user. For example, if the initial userinterface (200, FIG. 2) is displayed, only the first-level data itemshave been parsed. When a subordinate data indicator 212 is actuated, thesecond-level data items are parsed and the second-level table 300 isbuilt and displayed.

To accomplish the dynamic creation of tables, dynamic X-paths are usedto keep track of previous data. X-paths are an XML concept that providea way to find data. If a level of data items has been previouslyaccessed, a dynamic X-path is stored that keeps track of that level ofdata items. When a subordinate data level is accessed, a table (or othertype of display) is built and displayed. The subordinate data level isappended to the dynamic X-path so that the data items in that data levelcan be easily located the next time they are required.

At block 600, the first-level—or parent—table is built and displayed byparsing the first-level data items of the hierarchical data set. Thismay be accomplished using a non-recursive version of the algorithmpreviously discussed in relation to FIG. 5. When a subordinate dataindicator is actuated (block 602), the parent table is retrieved usingthe dynamic X-path. A dynamic X-path associated with the parent table isretrieved at block 604. From the dynamic X-path, it can be determined ifthe subordinate data level has been previously access and, therefore,parsed and displayed. If the subordinate data level has been previouslyaccessed (“Yes” branch, block 608), then the previously built table isdisplayed or hidden at block 616.

If the subordinate data level has not been previously accessed (“No”branch, block 608), then the subordinate data level data items areaccessed utilizing the dynamic X-path associated with the hierarchicaldata set at block 612. A table (or some other display format) is built(block 614). After the table is built, the table is displayed at block616.

By parsing the data and building the displays in this manner, large datasets can be parsed and displayed more efficiently than if the data isinitially parsed prior to the initial display.

Conclusion

Although the invention has been described in language specific tostructural features and/or methodological steps, it is to be understoodthat the invention defined in the appended claims is not necessarilylimited to the specific features or steps described. Rather, thespecific features and steps are disclosed as preferred forms ofimplementing the claimed invention.

1. A computer-implemented method for displaying hierarchical data, themethod comprising: displaying a first table that shows one or morefirst-level data items included in a hierarchical data set, thehierarchical data set expressed by a markup language, the first tablehaving a row corresponding to each first-level data item and one or morecolumns that each correspond to a first-level data sub-item associatedwith the first-level data item of a corresponding row; displaying atleast a portion of a second table that shows one or more second-leveldata items in the hierarchical data set, the second table having a rowcorresponding to each second-level data item and one or more columnsthat each correspond to a second-level data sub-item associated with thesecond-level data item of a corresponding row; displaying one or moreactuatable subordinate data icons, each in a column of a row in thefirst table that, when actuated, causes at least a portion of the secondtable to be displayed; and wherein the actuatable subordinate data iconis only displayed if there is second-level data that corresponds withthe first-level data sub-item associated with the column in which theactuatable subordinate data icon is displayed.
 2. The method as recitedin claim 1, wherein a row in the first table that contains the actuatedsubordinate data icon remains visible after the second table isdisplayed.
 3. The method as recited in claim 11, further comprising:displaying at least a portion of a third table that shows one or morethird-level data items in the hierarchical data set, the third tablehaving a row corresponding to each third-level data item and one or morecolumns that each correspond to a third-level data sub-item associatedwith the third-level data item of a corresponding row; displaying one ormore actuatable subordinate data icons in the second table, each in acolumn of a row in the second table that, when actuated, causes at leasta portion of the third table to be displayed; and wherein the actuatablesubordinate data icon is only displayed in the second table if there isthird-level data that corresponds with the second-level data sub-itemassociated with the column in which the actuatable subordinate data iconis displayed.
 4. The method as recited in claim 3, wherein a row in thesecond table that contains the actuated subordinate data icon remainsvisible after the third table is displayed.
 5. One or morecomputer-readable media containing computer-executable instructionsthat, when executed on a computer, perform the following steps: buildinga first-level display for a first level of data in the hierarchicaldata, the hierarchical data expressed by a markup language, thefirst-level display having one or more actuatable subordinate dataindicators that are displayed for each data item that has second-leveldata associated with it; displaying the first-level display; when asubordinate data indicator is actuated, building a second-level displayfor the second level of data in the hierarchical data that is associatedwith the data item corresponding to the subordinate data indicator thathas been actuated; and displaying the second-level display.
 6. Thecomputer-readable media as recited in claim 5, wherein the hierarchicaldata is extensible markup language (XML) data.
 7. The computer-readablemedia as recited in claim 5, further comprising computer-executableinstructions that, when executed on a computer, perform the followingsteps: including a second-level subordinate data indicator in thesecond-level display for each data item that has third-level dataassociated with it; when a second-level subordinate data indicator isactuated, building a third-level display for the third level of data inthe hierarchical data that is associated with the data itemcorresponding to the second-level subordinate data indicator that hasbeen actuated; and displaying the third-level display.
 8. Thecomputer-readable media as recited in claim 5, further comprisingcomputer-executable instructions that, when executed on a computer,perform the following steps: determining if the second-level display hasbeen previously created; and creating the second-level display only ifthe second-level display has not previously been created.
 9. Thecomputer-readable media as recited in claim 8, wherein the determiningif the second-level display has been previously created furthercomprises referencing a data path that indicates whether thesecond-level display has been previously created.
 10. Thecomputer-readable media as recited in claim 8, wherein the determiningif the second-level display has been previously created furthercomprises referencing a data path that indicates whether thesecond-level display has previously been created, and wherein the methodfurther comprises appending information to the data path when thesecond-level display is created if the second-level display has notpreviously been created, the information indicating that thesecond-level display has been created.
 11. A system configured todisplay hierarchical data, the system comprising: a processor; and amemory into which a plurality of computer-executable instructions areloaded, the plurality of instructions performing a method comprising:building a first-level display for a first level of data in thehierarchical data, the hierarchical data expressed by a markup language,the first-level display having one or more actuatable subordinate dataindicators that are displayed for each data item that has second-leveldata associated with it; displaying the first-level display; when asubordinate data indicator is actuated, building a second-level displayfor the second level of data in the hierarchical data that is associatedwith the data item corresponding to the subordinate data indicator thathas been actuated; and displaying the second-level display.
 12. Thesystem as recited in claim 11, wherein the hierarchical data isextensible markup language (XML) data.
 13. The system as recited inclaim 11, further comprising: including a second-level subordinate dataindicator in the second-level display for each data item that hasthird-level data associated with it; when a second-level subordinatedata indicator is actuated, building a third-level display for the thirdlevel of data in the hierarchical data that is associated with the dataitem corresponding to the second-level subordinate data indicator thathas been actuated; and displaying the third-level display.
 14. Thesystem as recited in claim 11, further comprising: determining if thesecond-level display has been previously created; and creating thesecond-level display only if the second-level display has not previouslybeen created.
 15. The system as recited in claim 14, wherein thedetermining if the second-level display has been previously createdfurther comprises referencing a data path that indicates whether thesecond-level display has been previously created.
 16. The system asrecited in claim 14, wherein the determining if the second-level displayhas been previously created further comprises referencing a data paththat indicates whether the second-level display has previously beencreated, and wherein the method further comprises appending informationto the data path when the second-level display is created if thesecond-level display has not previously been created, the informationindicating that the second-level display has been created.